THl^J AWAKENING OF THE SEED 11 



Weigh both sets of seeds (i. e., the control and 

 the others; there should be at least twenty in each 

 set), treat them with rubber or cement, and weigh 

 again. 



Before proceeding with the experiment, test the 

 seeds to see if the openings are stopped. Place some 

 untreated seeds in water (the control seeds must not 

 be used for this) , and heat until bubbles begin to issue 

 from the openings of all of them; then place the 

 treated seeds in the warm water; if no bubbles issue 

 from them we may consider it fairly certain that they 

 are satisfactorily^ closed; the heat must not be too 

 great or too prolonged, as it may in that case soften 

 the rubber so that the expanding air inside may force 

 an opening. Should any of the sealed seeds yield 

 bubbles, it is better to throw all the sealed seeds away 

 and prepare a fresh lot, until you succeed in getting 

 them all air-tight. 



Submerge all the seeds in cold water (the wire 

 spring shown in Fig. 16 is useful for keeping them 

 under water; the seeds may be placed in it and 

 weighed, together with the spring, thus making it un- 

 necessary to handle them separately) . Remove the 

 seeds at frequent intervals, dry them on the surface 

 and weigh both sets, to see which is absorbing water 

 more rapidly. Any seeds with cracks in the covers 

 must, of course, be rejected. At the end of the 

 experiment, place the seeds again in warm water, to 



